As a method of measuring ion channels depending on cell membrane electrophysiologically, a substrate type probe making use of ultrafine processing technology has been noticed. Unlike the conventional micropipette, it does not require skilled operation for inserting a micropipette into individual cells, and it is suited to an automated system of high throughput.
For example, as shown in FIG. 26, the existing cell electrophysiological sensor 1 (substrate probe) includes a substrate 2 and an electrode jar 3 disposed above the substrate 2. The substrate 2 has a through-hole 5 penetrating through the substrate 2 from its upside to downside.
Inside of the electrode jar 3, a first electrode 6 is disposed, and a second electrode 7 is disposed inside of the through-hole 5. The second electrode 7 is coupled to a signal detector (not shown) by way of a wiring 8.
The operating method of the cell electrophysiological sensor 1 is explained below.
First, an electrolyte solution 9 and a sample cell 10 are poured into the electrode jar 3. The sample cell 10 is trapped and held at an opening 4 of the through-hole 5.
At the time of measurement, the sample cell 10 is sucked by a suction pump or the like from beneath the through-hole 5, and is held in contact with the opening 4. This through-hole 5 plays the same role as the leading end hole in the micropipette. The function and pharmacological reaction of the ion channel of the sample cell 10 are analyzed by measuring the voltage or current before and after reaction between the first electrode 6 and second electrode 7, and determining the potential difference inside and outside of the cell (see, for example, patent document 1).
However, in the conventional cell electrophysiological sensor 1, the flow of electrolyte solution 9 flowing in and out of the through-hole 5 is poor, and the rate of trapping the sample cell 10 is low.
Since the through-hole 5 is very fine, and the flow passage suddenly changes in the sectional area at the interface of electrode jar 3 and through-hole 5, and the resistance loss of the fluid increases. As a result, the sample cell 10 cannot be sucked accurately, and the trapping rate declines.    [Patent document 1] International Patent Application Laid-Open No. WO02/055653 pamphlet